Support for —target ES2016, —target ES2017 and —target ESNext

TypeScript 2.1 supports three new target values —target ES2016, —target ES2017 and —target ESNext.

Using target —target ES2016 will instruct the compiler not to transform ES2016-specific features, e.g. ** operator.

Similarly, —target ES2017 will instruct the compiler not to transform ES2017-specific features like async/await.

—target ESNext targets latest supported ES proposed features.